A critical, yet understudied, aspect in young people with chronic health conditions is successful transition to adult medical care. This care transition in childhood cancer survivorship has become increasingly important as almost 80% of children with cancer are cured, but most will experience at least one disease or treatment- related morbidity. The majority of adult survivors of childhood cancer do not receive recommended cancer- related follow-up care or screening for potential long-term life-threatening health consequences that increase with age. Consensus statements have emphasized the importance of, and provided recommendations for, transition to adult care for youth with chronic illness. Yet, no clear evidence-based guidelines exist for how best to assess when, or if, an individual is prepared to transition to adult medical care. While transition checklists have been developed that assess disease knowledge and skills as markers of transition readiness, these measures do not address the developmental, psychosocial, and systemic complexities of the transition process, nor do they assess transition readiness from all stakeholders' (i.e., patients, parents, providers) perspectives. To address this limitation, our multidisciplinary team developed a model of transition readiness for AYA survivors-the Socio-ecological Model of AYA Readiness for Transition (SMART). The aims of the study are to use mixed methods (qualitative and quantitative) to refine SMART and develop a content valid instrument of transition readiness of adolescent and young adult (AYA) survivors of childhood cancer-the Transition Readiness Inventory (TRI)-that will measure SMART components. TRI assessment will be multi- informant, with three versions created for patients, parents, and providers (PPP). Focus groups with PPP will elicit multiple perspectives on AYA survivor transition readiness and will inform SMART modifications (Aim 1). Through an iterative process of item development, and qualitative data collection and analysis (content validity ratings, cognitive think aloud interviews) with PPP from The Children's Hospital of Philadelphia (CHOP) and non CHOP PPP, three TRI versions for PPP will be developed (Aim 2). Finally, a clinic-based pilot study (N=50 PPP triads) will test the initial psychometrics of the TRIs and the feasibility of multi-informant on-line data collection (Aim 3). NIH's Patient-Reported Outcomes Measurement Information System (PROMIS-an NIH roadmap initiative) will inform the methods of the study via adoption of their measurement development procedures, use of their on-line data capture system, and the administration of PROMIS items to contribute to the assessment of the concurrent validity of TRI. The long-term programmatic research aims following completion of the current project are to conduct a large-scale validation study of TRI and to translate findings to inform interventions and evidence-based guidelines to facilitate transition to adult care of AYA survivors. These goals are consistent with PA 09-130, Exploratory Grants for Behavioral Research in Cancer Control, and the NCI's commitment to enhancing health outcomes and care transitions of AYA survivors. PUBLIC HEALTH RELEVANCE: Addressing the challenge of transition to adult medical care for youth with chronic health conditions, including cancer, has been highlighted at a national level (e.g., National Cancer Institute and LIVESTRONG joint report, 2006; Healthy People 2010 and 2020; congressional bill H.R. 2109; multiple medical organization consensus statements). Studying transition to adult medical care for adolescent and young adult survivors of childhood cancer is especially important given: (1) the number of childhood cancer survivors in the U.S. is approaching 300,000 and increasing, (2) the high prevalence or risk for significant long-term cancer-related morbidities, and (3) the fact that most adult survivors do not seek recommended cancer-related medical care. Thus, the proposed project has significant public health implications for advancing the study of transition in childhood cancer survivorship and other conditions to ultimately improve disease management and continuity of care.